Measurement of double polarisation asymmetries in $\omega$-photoproduction

The first measurements of the beam-target-helicity-asymmetries $E$ and $G$ in the photoproduction of $\omega$-mesons off protons at the CBELSA/TAPS experiment are reported. $E$ ($G$) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. $E$ was measured over the photon energy range from close to threshold ($E_{\gamma }=1108$~MeV) to $E_{\gamma }=2300$~MeV and $G$ at a single energy interval of $1108 < E_\gamma <1300$MeV\mathrm{.}Bothmeasurementscoverthefullsolidangle\mathrm{.}Theobservables$E$and$G$arehighlysensitivetothecontributionofbaryonresonances,with$E$actingasahelicityfilterinthe$s$-channel. The new results indicate significant $s$-channel resonance contributions together with contributions from $t$-channel exchange processes. A partial wave analysis reveals strong contributions from the partial waves with spin-parity $J^P=3\mathrm{/}{2}^{+},5\mathrm{/}{2}^{+}$, and $3\mathrm{/}{2}^{-}$.